Just before midnight Wednesday, three words brought a stream of emergency crews and hazardous materials units to a wooded corner of Cecil County just north of Interstate 95: liquid sulfuric acid.

A train operated by CSX Corp. derailed about 11:45 p.m., and initial reports said two cars contained the highly corrosive and environmentally dangerous substance.

Luckily, officials said, the acid didn't leak, even though the cars containing it were off-kilter.

"They were either sideways or just off the rail, but none are on their side," said CSX spokesman Bob Sullivan of the nine cars determined to have slipped off the tracks.

The derailment comes as the federal government investigates another recent CSX train derailment in Maryland that killed two young women.

Emergency crews from three states responded to Wednesday's incident, including the Cecil County Department of Emergency Services' hazardous materials team and units from Elkton and North East, Newark, Del., and West Grove, Pa., the county department said.

Officials at the state Department of the Environment also sent their own hazardous materials experts to oversee the process of righting the cars containing the acid without causing a leak, said Jay Apperson, a department spokesman.

No injuries were reported, and there was no danger to residents in the area, near Route 213 north of Elkton. That road was closed by the emergency response.

Sullivan said the 90-car train, pulled by three locomotives, was traveling from Selkirk, N.Y., to Hamlet, N.C. Aside from the cars full of acid, the train carried cars with boxed merchandise and covered hoppers full of iron ore.

The railroad expected to clear the derailment by Thursday night, Sullivan said. The cause will continue to be investigated.

The derailment came nearly six months to the day after another CSX train derailed in historic Ellicott City in Howard County, killing two college students who were sitting on a railroad bridge over the former mill town's Main Street and raising concerns about the safety of CSX rail lines throughout the region.

Just before midnight on Aug. 20, 21 cars of an 80-car coal train jumped the tracks, burying Ellicott City natives Elizabeth Nass and Rose Mayr, both 19, and the street below in coal.

A massive cleanup followed.

A preliminary report on the derailment released by the National Transportation Safety Board in September appeared to focus on track conditions, further stoking concerns about safety. The report named the Brotherhood of Maintenance of Way Employees, a union whose members handle track maintenance, as a party to the investigation.

The report showed the train was traveling at the speed limit of 25 mph at the time of the derailment.

Eric Weiss, a NTSB spokesman, said the Ellicott City derailment investigation was continuing but could not say when the final report would be released. The NTSB is not investigating the Elkton derailment, he said.

Sullivan said CSX did not have any updates on the Ellicott City derailment, either, and is awaiting the NTSB report.

Last year, CSX experienced 130 derailments from January through November, according to the most recent data available from the Federal Railroad Administration, the regulatory agency for the industry.

The Ellicott City derailment caused more than $735,000 in equipment and track damages. Initial estimates put total damages, including environmental remediation costs, at about $2.2 million.